1. Field of the Invention
The present invention generally relates to network communication, and specifically relates to large-scale network communication using LANs and WAN.
2. Description of the Related Art
Recently, a wide area network (WAN) has been increasingly used. The WAN connects local area networks (LANs) to which a plurality of terminal devices is communicably connected, and allows the terminal devices on the different LANs to hold communication therebetween. The WAN, which is also referred to as “Inter-LAN connection”, enables a large-scale network to be easily constructed by connecting existing LANs to one another.
Similarly to packet communication in the LAN, an error possibly occurs in packet communication in the WAN. Japanese Patent Application Laid-open No. 2000-299712, for example, discloses a data communication system capable of reducing communication errors that occur in packet communication in the WAN by a selected optimum error correcting method.
According to the conventional error correcting method, the result of calculation made based on packet data is added to a packet as redundant data in advance. If the redundant data does not match the result of recalculation made when the packet is received, it is determined that the packet contains an error.
However, with the conventional technique represented by the method disclosed in Japanese Patent Application Laid-open No. 2000-299712, when it is determined that a packet contains an error and the error cannot be corrected, a receiver communication apparatus discards the packet. Due to this, if a WAN-side link frequently causes minor errors as seen in a microwave-multiplex radio link, a receiver LAN is unable to receive packets.